Refactored tasks.py to split out letters_pdf tasks

- Added has_permission helper in models.py to check permission in service
- Moved letters pdf tasks to separate file
- Moved letters pdf tests to own file

app/celery/letters_pdf_tasks.py

@@ -0,0 +1,68 @@
+from flask import current_app
+from requests import (
+    post as requests_post,
+    RequestException
+)
+
+from botocore.exceptions import ClientError as BotoClientError
+from sqlalchemy.orm.exc import NoResultFound
+
+from app import notify_celery
+from app.aws import s3
+from app.config import QueueNames
+from app.dao.notifications_dao import get_notification_by_id, update_notification_status_by_id
+from app.statsd_decorators import statsd
+
+
+@notify_celery.task(bind=True, name="create-letters-pdf", max_retries=15, default_retry_delay=300)
+@statsd(namespace="tasks")
+def create_letters_pdf(self, notification_id):
+    try:
+        notification = get_notification_by_id(notification_id)
+        if not notification:
+            raise NoResultFound()
+
+        pdf_data = get_letters_pdf(
+            notification.template,
+            contact_block=notification.reply_to_text,
+            org_id=notification.service.dvla_organisation.id,
+            values=notification.personalisation
+        )
+        current_app.logger.info("PDF Letter {} reference {} created at {}, {} bytes".format(
+            notification.id, notification.reference, notification.created_at, len(pdf_data)))
+        s3.upload_letters_pdf(reference=notification.reference, crown=True, filedata=pdf_data)
+    except (RequestException, BotoClientError):
+        try:
+            current_app.logger.exception(
+                "Letters PDF notification creation for id: {} failed".format(notification_id)
+            )
+            self.retry(queue=QueueNames.RETRY)
+        except self.MaxRetriesExceededError:
+            current_app.logger.exception(
+                "RETRY FAILED: task create_letters_pdf failed for notification {}".format(notification_id),
+            )
+            update_notification_status_by_id(notification_id, 'technical-failure')
+
+
+def get_letters_pdf(template, contact_block, org_id, values):
+    template_for_letter_print = {
+        "subject": template.subject,
+        "content": template.content
+    }
+
+    data = {
+        'letter_contact_block': contact_block,
+        'template': template_for_letter_print,
+        'values': values,
+        'dvla_org_id': org_id,
+    }
+    resp = requests_post(
+        '{}/print.pdf'.format(
+            current_app.config['TEMPLATE_PREVIEW_API_HOST']
+        ),
+        json=data,
+        headers={'Authorization': 'Token {}'.format(current_app.config['TEMPLATE_PREVIEW_API_KEY'])}
+    )
+    resp.raise_for_status()
+
+    return resp.content